When to use "contro di" as opposed to only "contro"?

Question

I know it is correct to say "contro di lui", but "contro il nemico". Why? Is it because in the first case the object is a pronoun and in the second case it is a noun?

Answer 1

Yes, when using it with a personal pronoun you need to use the preposition "di", while with a noun you can use it with an article or even without, if it's a first name.

• Contro DI lui (personal pronoun)
• Contro UN ragazzo (noun)
• Contro Luca (first name)